The invention relates to a mobile radiotelephony device intended for accommodating a user identification module, where the device has an established link to an identification module to thereby prevent a normal operation of the device when an identification module other than the linked identification module is mounted inside the device.
The invention also relates to a method of protecting such a device, and a computer program for implementing such a method.
The invention notably has applications in the field of portable radiotelephony. Portable radiotelephony devices are intended to accompany their users when they move around. It happens that these devices are lost or stolen.
U.S. Pat. No. 5,913,175, published Jun. 15, 1999 describes a method of protecting a radiotelephone which permits to avoid that the lost or stolen telephone can be used by a third party with another user identification module. This method comprises establishing a link between the device and a specific user identification module and blocking the normal operation of the device when the user identification module that is placed inside the device is not the one that is linked to the device.
When the device is lost or stolen with the identification module to which it is linked, the user is to warn the operator so that the use of his identification module is blocked at network level.
This means that the device can be freely used until the identification module to which it is linked is blocked via the network. This may take a certain period of time.
It is notably an object of the invention to resolve this problem. For this purpose, a device in accordance with the invention (1) verifies a user identification module mounted inside the mobile radiotelephony device is linked to the mobile radiotelephony device, (2) detects a period of inactivity of the mobile radiotelephony device during a normal operation of the mobile radiotelepony device, wherein the normal operation includes a processing of all outgoing calls, and (3) prevents the normal operation of the mobile radiotelephony device in response to the verification of the user identification module and in response to the detection of the period of inactivity of the mobile radiotelephony device.
Thus, when the device falls into the hands of a third party together with the identification module to which it is linked, it has most probably been inactive for a period of time that is sufficiently long for its normal operation to be blocked (advantageously, the inactive time after which the blocking means are activated is of the order of several minutes). The device cannot thus be used without the deblocking code being supplied.
Thanks to the invention the lost or stolen device becomes totally unusable. A fraudulent person cannot send communications at the cost of the owner of the device. But neither can he use the device with another identification module. The theft of the device becomes totally useless. The invention thus forms a protection against theft.
In a particularly simple embodiment, the connecting means comprise reading means and storage means of a data stored in the identification module, and the test means compare the thus stored data with the data stored in the identification module which is places inside the device. The data stored is formed, for example, by the international identification number IMSI which is contained in the identification module (compare standards relating to the GSM radiotelephony systems). Thus, the identification module is automatically linked to the device without the intervention of the user, more particularly without the fact that a specific code has to be entered.
Advantageously the deblocking code, which is to be supplied to return to the normal operating mode, is formed by the pin code (Personal Identity Number) which is contained in the identification module (compare standards relating to the GSM radiotelephony systems). Thus the user need not store an additional code to ensure the protection of his device.